hobbs



0. HOBBS. v MOLDING AND CASTING STEREOTYPE PLATES.

No. 8,333. Patented Sept. 2, 185 1.

UNITED sTA'rEs CHAS. HOBBS, or NEW YORK, N. Y.

MOLDING AND CASTING STEREOTYPE-PLATES.

Specification of Letters Patent No. 8,333, dated September 2, 1851.

To all whom it may concern.

Be it known that I, CHARLES HOBBS, of the city and county of New York,have invented a new and Improved Method of Molding and CastingStereotype-Plates from Type, Woodcuts, Medals, &c., and I do herebydeclare that the following is a full and exact description.

The nature of my invention consists in molding and casting any givennumber of stereotype plates at one operation: besides making them morerapidly than can be made by any other known method, it makes them moreperfect.

I will state some of the advantages it possesses over the usual methodof molding and casting. First, I exhaust the air from the plaster andfrom the type before I apply the plaster to the type, when making molds.The usual way is to roll the air from the plaster and face of the typeby hand, after the plaster has been applied to the type. This can not bedone without forcing the plaster into some parts harder than in others,which will cause the plaster to adhere to the face of the type, andportions of it break off when the mold is drawn. Second, I mold a muchlarger number in the same time than can be made by any other knownmethod. I also save material by making the molds with two faces thusmaking one mold do instead of two. Third, in casting the molds I standthem on edge with a body of stereotype metal above them, thus having thelargest body of metal above the molds. The usual method of casting is,to leave the edges and the corners of the casting pan open for the metalto run in and lay the mold down on a piece of flat iron which fits thebottom of the casting pan, thus when the metal runs into the corners thepiece of iron floats and brings the mold directly in contact with thecover of the pan, thus leaving the largest body of metal below themolds, this leaves them liable to hollows in the face, calledshrinkages, and also to places where the air and steam has lodged calledblows. This is prevented in my method, by the largest body of metalbeing above the molds the shrinking always taking place where thelargest body is, and the molds being placed on edge leaves little or noopportunity for the air or steam to lodge near them. Fourth, when I putmy pan in the pot of fluid metal I do not box, but in the usual method-it requires considerable. In my apparatus I can cast ten or even twentytimes as many as can be cast in the usual way and I have only to takeoff the top wedge and two side wedges in order to release the whole ofthem, whereas in the usual way they have to knock off all the metalaround the edge of each cast (which only contains one layer where minecontains ten) before they can get at the plates. Sixth, in my apparatusthe molds are stood on edge and having two faces the metal flows alikeon both sides thus the pressure of metal is equal on both sides of themolds this prevents the molds from breaking while they are being cast.In the method now used the pressure comes on but one side of the moldand anything lodging on the back part of the mold sufficient to causeunevenness, will cause the mold to break thus spoiling the plate, thisis quite a discount on the present mode of casting. Seventh, I can castwith the metal at a much lower heat than can be done by the presentmethod. In the present method they bring the face perfect by heat andthey very often over heat the metal causing a bad face to the plate, andoxidizing the metal. I pre vent this by not requiring so much heat butbringing the face perfect by the weight of metal confined-over themolds.

To enable others skilled in the art to make and use my apparatus orinvention I will proceed to describe its construct-ion and operation.

Figure 1 in the annexed drawings is the molding apparatus; Fig. 2, thecasting ap- 'paratus.

Letter A the air tight molding box; B, an air tight cylinder forexhausting the air from the plaster; C, a funnel to admit the plasterinto the cylinder; D, D, the flasks (open and closed) that contain themolds; E, the casting box; F, a rack to put over the molds when in thecasting box, to prevent them from floating against the cover of the box.

Gr, is the cover of casting box.

H represents the molds when taken from the flasks.

Having now described the use of the main parts I will proceed todescribe its sections and its operation. The forms of type, wood cuts,medals, &c. having been previously oiled and prepared to receive theplaster, I put them in box A with a flask between every two forms asrepresented in the drawing letter a standing them upright with the mouthof the flasks next to the top of the molding box. The mouths of theflasks are covered with india rubber on the upper side so that when itcomes in contact with the top of the box forms a tight joint. There areopenings in the top of the box to correspond with the mouths of theflasks. After I have filled the molding box with forms I close the coveragainst the open edge of the box Z) b which is also covered with indiarubber and then attach the clamp 0 to the projections on the side ofmolding box tight- I ening the screw in the clamp against the cover,until it has compressed the india rubber sufficient to make the jointair tight. I now draw the rod (l it being attached through a stuflingbox to cut off plate 6 this opens the connection between the flasks andpipe f there being openings in the cut off to correspond with the numberof flasks in the molding box. (Thus, if I had but one flask in the box Iwould use the plate 6 with one opening and if four flasks the plate awith four openings.) After drawing the rod (Z with cut off plate 6 Iopen valve 9 and h then pour water into funnel C until the wholeapparatus is filled with water as far as valve g; I then close valve 9and pump the water out. This leaves a vacuum in the whole apparatusbetween the pump 2' and valve 9. I now tighten the screws m, m, whichhave rods working through stufling boxes against the forms and flasks inthe box, this forces them closely together, they having been leftpartially open in order to let the water run from them, its nownecessary that they should be tight to keep the plaster from running outof the flasks. This being done I mix the plaster with water and pour itin funnel C then shut valve h which prevents the plaster from runningout of the cylinder B. I then open valve 9 and the plaster then runsinto the cylinder; I shut the valve 9 before the plaster has quite runfrom the funnel this prevents the air following the plaster into thecylinder I then rapidly turn the crank j which is attached to apropeller inside of the cylinder B, this agitates the plaster andseparates the air from it. The crank is connected with the propeller bypassing through a stuffing box at one end of the cylinder where thecover is attached. The cover at the end of the cylinder is made to fitair tight by means of a spherical joint and can be taken off or put onby turning it round, there being wedge pieces on the side, which fitinto the clamps 011 the side of the cylinder. This is for cleaning itout with facility in case of accident or when it may require it. The airbeing now taken from the plaster I open valve h the plaster-now flowsfrom the cylinder into pipe f from pipe f into the flasks in the moldingbox, which confines the plaster to the face of the type, wood cuts, &c.The molds are now made. In order to clean it out before the plaster hasbecome hard I push in rod cZwhich cuts off the connection between themolding box and the apparatus above it. I then shut 'valve 71, and" openvalve 9 after this I pour water into funnel C until it is filled, thenwash the plaster from the funnel and turn crank a minute or so, thenloosen the screw at the end of pipe f and take out bonnet Z openingvalve h. I then turn crank 7' until the water has all run out at the endof pipe f. The apparatus now being washed clean I take out the cutoffplate 6 and stand it to dry. The plate is taken out of the opening inpipe The cut off plate and inside of pipe f should be oiled when dry tokeep them from rust. After I have washed the apparatus I take off clamp0 and let down the cover. I then take out the forms in pairs with theirflasks between them lay them on a level bed of stone then take fourwedges or screws and insert one under each corner of the top form andforce it from the mold after this I insert the wedges or screws underthe flask, and force it from the bottom form. I now take out the pins inthe two corners of the flask and draw the two pieces apart (asrepresented in the annexed drawings D, D) this liberates the mold readyfor use.

Having described the operation of molding I will proceed to describe thecasting. I first take the molds and place them in an oven to dry, I thentake the casting apparatus (Fig. 2) and place it in a pot of fluid typemetal (sufliciently large to immerse the whole casting box as far as thecolumn), I let it remain there until it is heated to the sametemperatureas the type metal, I then inspect the molds in the oven, andif dry enough to cast I take the casting box out of the metal, and takeit apart. I then cleanse each part of it from dirt or dross that mayhang to it. on the side of the metal pot, putting in the two wedges 0 atthe sides of the box and then the two grooved at the two ends. Thegrooved wedges n are made so that the partitions can slide in easily andyet be tight, this necessary precaution is, that the plates may be of aneven thickness. After putting I now stand the casting box E thepartition plates into the grooved wedges n n I take the molds out of theoven and place them between the partition plates until the casting boxis filled, I then cover the top of the molds with rack F which preventsthe molds from raising when the metal is applied to them. I next takesome plaster of paris and lay it around in groove 7) at the top of thecasting box. I then put on the cover G placing the bead on the underpart of the cover (marked 9 9) directly into the groove 19, p, (on thetop of the plaster). I now fasten the two clamps 9' on the box andtighten the two screws against the cover, this forces the head 9 Qfirmly into the plaster in groove 2 7) thus making a joint sufficientlytight that the metal can not run through it. I now lift the wholeapparatus into the metal pot by means of a crane made for that purpose.I then sink the casting box into the fluid metal beyond valve 3 thenopen valve 3 by means tof the lever 25 and this admits the metal to themolds, after the box has filled as far as the column with metal, I closevalves .9 and fasten it by means of ratchet u then let it remain in themetal until the air and moisture has escaped through the column at thetop of the box. I then fill the column with metal and let it remain fiveor ten minutes; after this, I lift it out of the metal into a coolingtrough, by means of the crane. I let it remain there until the metal hasgot hard, I then lift it out of the cooling trough by means of pulleysattached to the ceiling. I now take off the clamps r and then the coverGr, after this I turn the box on its side and take a hammer and strikethe column of metal until I have jarred the contents of the box loose, Ithen remove the box turning its contents out on its side then I forceoff the top wedge 0 and afterwards the two end grooved wedges n n. I nowseparate each layer of plates by lifting the partition plates of ironthat separate them. The plates are now ready to be cleansed from theplaster and sent to the finishing room. In order to relieve the rack Ffrom the metal which surrounds it I throw it into the metal pot where itmelts off.

lVhat I claim as my invention and desire to secure by Letters Patentis 1. The molding in plaster of one, or more forms of type, wood cuts,medals, &c., at one operation in air tight vessels by means ofexhaustion.

2. I claim the making of the plaster molds with two faces.

3. I also claim the casting from one or more molds in a box suflicientlytight to hold fluid metal and bringing the face perfect by means of theweight of fluid metal confined above them in column, or otherwise.

4. I also claim the grooved wedges for retaining the molds in theirplaces while casting from them.

5. I also claim the non admission of fluid metal to the molds until theorifice through which it enters is sunk beneath the surface of the fluidmetal thus preventing the dirt and dross from entering with it.

CHARLES HOBBS.

WVitnesses: I JOHN GILBERT, LYMAN D. C. WILEY.

